As far as water content detection of stored-grain is concerned, cross-hole radar tomography method is used to find the abnormal water content areas in granary. Based on the basic theory of tomography, wave front ray tracing methods have been studied. Travel-time equation is used to correct refraction points before ray tracing, which improves the precision of ray tracing, and is also easy to realize. Velocity and attenuation tomography forward model were built respectively, and Least Square QR-factorization (LQSR) image rebuild methods were adopted to solve the inversion equation. Meanwhile, the properties of the two ray tracing methods were analyzed. Simulation and experimental results show that, compared to traditional methods, there is a better performance for the improved ray tracing proposed in this paper. It's proved that using cross-hole radar tomography method to detect the internal structure of huge granary is feasible
